1. Field of the Invention
This invention relates to an image reading apparatus for causing reflected light or transmitted light obtained by applying light to an original to be imaged on a line-shaped photoelectric conversion element (hereinafter referred to as the image sensor) to thereby read an image on the original, and is applied, for example, to an image forming apparatus or the like for effecting image formation with respect to the read image.
2. Related Background Art
Heretofore, reflected light or transmitted light obtained by applying light to an original on a copier or an image reading apparatus such as an image scanner has been imaged on an image sensor or a photosensitive body by the use of a lens or the like to thereby read an image.
A method whereby the image reading apparatus (hereinafter referred to as the image scanner) reads an original will hereinafter be described with reference to FIGS. 3 and 4 of the accompanying drawings.
FIG. 3 is a schematic view of the image scanner, and FIG. 4 is a cross-sectional view taken along the arrow A of FIG. 3.
It is to be understood that the widthwise direction of an optical scanning unit U as image reading means is X direction, the lengthwise direction of the optical scanning unit U is Y direction, and a direction forming right angles with X and Y directions is Z direction. In FIGS. 3 and 4, arrows indicating the directions are shown.
In FIGS. 3 and 4, a sheet original P is placed on the original supporting surface of an original glass table 10 as the light transmitting member of the image scanner 50 with its original reading surface facing the original glass table 10 side. The sheet original P is irradiated by the light source 1 of the optical scanning unit U, and the reflected light thereof is imaged on an image sensor 3 through a Selfoc lens 2 (trademark, hereinafter referred to as SLA) to thereby read an image corresponding to one line of the sheet original P.
The optical scanning unit U is caused to scan in X direction along the original glass table 10 to thereby read the whole image of the sheet original P (U to Uxe2x80x2).
The optical scanning unit U is comprised of an optical unit 7 comprising the light source 1, SLA 2 and the image sensor 3, and a scanning unit 6. The scanning unit 6 biases the optical unit 7 toward the original glass table 10 (in Z direction) by biasing means 5.
The scanning unit 6 is engaged with a driving rail 4 supported on the apparatus, and is driven along the original glass table (original mount glass) 10. When the driving rail 4 is at one end portion of the widthwise direction of the scanning unit 6, a sliding portion 8 is provided at the other end of the widthwise direction of the scanning unit 6, and slides on a rail portion 31 on a bottom cover 30 (in the figures, the rail portion 31 and the bottom cover 30 are shown as the same member, but may be discrete members).
On the other hand, when as shown in FIG. 5 of the accompanying drawings, the driving rail 4 is in the substantially central portion of the scanning unit 6, the sliding portion 8 as shown in FIG. 4 may not be provided. Also, in the constructions shown in FIGS. 4 and 5, a leaf spring is used as the biasing means 5, but a coil spring or the like can also be used to obtain a similar effect.
The original glass table 10 of the image scanner 50 may be stuck on an upper cover 20 by the use of a both-surface tape (not shown) or the like (see FIGS. 4 and 5), or may be held on the bottom cover 30, as shown in FIG. 6 of the accompanying drawings.
In the method shown in FIG. 6, the upper cover 20 is not provided, but an abutting member 21 against which the end portion of the sheet original P abuts is stuck on the original glass table 10 held on the bottom cover 30 by means of a both-surface tape or the like to thereby take a countermeasure for the getting-into (passing-through) of the sheet original P.
The optical unit 7 has a projected portion 9 abutting against the original glass table 10 outside the reading area of the image sensor 3 in order that the positioning of the original glass table 10 and the optical unit 7 may be done accurately and the two may not directly abut against each other.
The optical unit 7 is always biased toward the original glass table 10 by the biasing means 5 and therefore, by making the dimensions of the projected portion 9 accurate, the positioning of the original glass table 10 and the optical unit 7 can be done accurately.
Further, because of a construction in which the optical unit 7 is biased toward the original glass table 10, it is not necessary to install the original glass table 10 substantially in parallel, i.e., horizontally, to the plane in which the image scanner 50 is installed. That is, even if the original glass table 10 is installed substantially vertically to the plane in which the image scanner 50 is installed, an image can be read without any problem.
FIGS. 7 and 8 of the accompanying drawings show schematic views in which the original glass table 10 is installed substantially vertically to the plane in which the image scanner 50 is installed. FIG. 7 is a schematic view illustrating the vertically placed state of the image scanner 50, and FIG. 8 is a view taken along the arrow Axe2x80x2 in FIG. 7.
When the image scanner 50 is vertically placed as described above, the fore of the apparatus is supported by a vertically placing member 51 and the protruding portion 22 of the exterior package is used for the supporting of the rear of the apparatus. It is possible to change the shape of the protruding portion 22 to thereby vertically place the image scanner 50 in a state inclined with respect to the horizontal within the range of angle of xcex8xe2x89xa690xc2x0.
However, in the case of the prior art as described above, the following problems have arisen.
When as shown in FIG. 9A of the accompanying drawings, the sheet original P is disposed on the vertically placed image scanner 50, the lower end portion of the sheet original P is sometimes not supported in contact and the sheet original P cannot be disposed easily.
It is because the sheet original P is not well placed on an abutting surface 23a (or 21a) on which the lower end portion of the sheet original P abuts against an edge portion 23 as the abutting portion of the upper cover 20 holding the original glass table 10 thereon (or the stuck abutting member 21), and as shown in FIG. 9B of the accompanying drawings, the sheet original P deviates and slips down from the abutting surface.
It has also happened that the lateral end portion of the sheet original P when the image scanner 50 is vertically placed does not abut against the abutting surface and the sheet original P is turned over.
The present invention has been made in order to solve the above-noted problems peculiar to the prior art and the object thereof is to provide an image reading apparatus and an image forming apparatus in which the disposition of a sheet original when vertically placed is made easy.
To achieve the above object, an image reading apparatus according to the present invention comprises:
an original supporting surface on which a sheet original is placed;
reading means for reading an image of the sheet original placed on the original supporting surface; and
an abutting portion which is provided on the original supporting surface and against which an end portion of the sheet original abuts;
wherein the abutting portion has a positioning portion for positioning the end portion of the sheet original so that when the original supporting surface is brought into an inclined state with respect to a horizontal, the sheet original may not float up relative to the original supporting surface.
Also, an image reading apparatus according to the present invention comprises:
an original supporting surface on which a sheet original is placed;
reading means or reading an image of the sheet original placed on the original supporting surface; and
an abutting portion against which an end portion of the sheet original placed on the original supporting surface abuts;
wherein the abutting portion has a positioning portion for positioning the end portion of the sheet original so that when the original supporting surface is brought into an inclined state with respect to a horizontal, the end portion of the sheet original placed on the original supporting surface may not deviate from the abutting portion and the sheet original may not slip down.
Also, an image reading apparatus according to the present invention is an image reading apparatus comprises:
an original supporting surface on which a sheet original is placed in a horizontally placed state of a main body of the apparatus; and
image reading means for reading the image of the sheet original placed on the original supporting surface; and
an abutting member against which an end portion of the sheet original abuts and is positioned so that in the vertically placed state of the main body of the apparatus, the sheet original may be held relative to the original supporting surface.